In recent years, the development of “keep-lane” technologies has been progressing. Such technologies are for preventing in advance deviations by vehicles of passenger cars, etc., from the lane markings at either the left or right of the driving lanes.
As such “keep-lane” technologies, the development of devices for controlling straying avoidance by determining the possibility of lane deviations have been advancing. Besides such efforts, the development of lane keeping assistance devices that automatically control so that the vehicle travels along the driving lane currently being advanced along, and travels following the lane markings (refer for example to Japanese Patent Application Publication No. Hei7-104850 (hereinafter “Patent Reference 1”), etc.) have also been progressing.
The first lane keeping assistance devices mostly accomplished automatic lane keeping assistance controls, so that the vehicles advanced at the middle of the driving lane, as well as along the center line within the traffic lane indicated at the vehicle's left-right. Such devices are similar to the one mentioned in Patent Reference 1.
However, the driver may want to travel while approaching the right or the left of the driving lane. In such a case, if the lane keeping assistance device automatically controls to follow the middle of the driving lane, discomfort may arise, and troublesomeness may be experienced.
A lane keeping assistance device is mentioned in Japanese Patent Application Publication No. 2001-39326 (hereinafter “Patent Reference 2”) with the aim of solving such a problem. Patent Reference 2 proposes a device so that, at traveling times when the device's lane keeping assistance control is not in operation, the lateral displacement data for the vehicle position in the sideways direction of the driving lane is collected. Then, the device learns the position of a driving lane which fits the driver's preference.
Additionally, Japanese Patent Application Publication No. 2004-231096 (hereinafter “Patent Reference 3”) proposes a lane keeping assistance device which establishes a target line which reflects the driver's preference based on the lateral displacement data collected using the above technique. The device makes the vehicle follow this target line.
However, with the lane keeping assistance device mentioned in Patent Reference 3, the target line cannot be changed when the driver is revising the vehicle's travel orbit by steering with the steering wheel. There are cases when discomfort arises at the driver's steering with the steering wheel, because the vehicle is continuously dragged to the previous target line.
It is conceivable to temporarily stop the lane keeping assistance control while the driver is steering with the steering wheel, in order to avoid the occurrence of such discomfort. However, then the function of the lane keeping assistance control is not exhibited. For example, if the driving lane curves, there is a possibility that the vehicle will stray from the lane markings.